Work function of hydrogen-terminated diamond surfaces under ion impact

Scanning Kelvin-probe microscopy is applied in ultra-high vacuum to characterise local changes in the work function of the hydrogen-terminated diamond surface following modification by thermal annealing and ion-implantation. The effect on the work function of hydrogen desorption was monitored during annealing. Ion irradiation was found to give rise to a different response, inconsistent with hydrogen removal. Increased ion fluence causes a rapid enhancement in the work function, each impinging ion causing band structure modification which extends over length scales of at least 20 nm beyond the impact site, considerably larger than the damage cylinder in the vicinity of each ion impact.